Embodiments of the present disclosure relate to a method of identifying deployment of a casing in a borehole, the method being of the type that processes sensor measurements to determine casing deployment. The present disclosure also relates to a casing deployment detection apparatus of the type that, for example, is configured to receive and process sensor data to determine casing deployment characteristics. The present disclosure also relates to a method of identifying cementing of a borehole, the method being of the type that, for example, processes sensor measurements to determine characteristics of the cementing. The present disclosure further relates to a cementing detection apparatus of the type that, for example, is arranged to receive an process sensor data regarding the cementing.
In the hydrocarbon extraction industry, during the course of a drilling program, the borehole typically has one or more “casing strings” run and cemented in place. A typical drilling program first involves drilling a large diameter borehole from the Earth's surface for several thousand feet. A “surface casing” string is then run into the borehole and cement is then pumped inside the casing and returns up through an annulus located between the casing and the borehole. After the cement in the annulus has cured or hardened, another drill bit is utilized to drill through the cement in the surface casing to drill a second and deeper borehole into the formations of the Earth. Typically, the subsequent drill bit has a smaller diameter than the initial drill bit such that the second borehole has a smaller diameter than the diameter of the surface borehole.
At an appropriate depth below the surface casing, the drilling of the borehole is discontinued and a string of pipe commonly called a casing or liner is inserted through the surface casing.
Again, cement is pumped inside the casing and returns up through the annulus, where it cures or hardens. When the cementing operation is completed and the cement sets, there is a column of cement in the annulus of the subsequent string of pipe. The casing strings are usually comprised of a number of joints, each being on the order of forty feet long, connected to one another by threaded connections or other connection means.
Casing the well aims to serve dual purposes: preventing the bore walls from collapsing and isolating the various geological strata and thus, avoiding exchange of fluids between them.
In the oilfield industry, there is a need to automate process and/or applications and to monitor the automated processes and applications. In particular, it is desirable to monitor certain oilfield activities either in real-time or monitoring data stored in a post-processing context. In this regard, casing and cementing are borehole activities that are expensive and time consuming. When conducting real-time analysis, failure to recognize that casing is in progress can delay the ordering of cementing capabilities and cause days. Sometimes such a failure can immobilize a drilling rig for weeks, negating any gains in drilling time otherwise made, for example by rate of penetration optimization.
Also, there is a growing desire in the oilfield industry to automate the drilling cycle: from the so-called “spud” to completion of a well. Automatic interpretation of drilling surface signals, signals made by measurement devices at the surface, therefore becomes a pre-requisite for this automation. In this respect, without proper detection of casing runs, automatic control cannot take place, because for example casing runs risk being confused with so-called “trips in”, and the bottom of a casing run risks being interpreted as a drill bit passing through and reaching the end of a run of casing ready to operate in an open hole below the casing. In an automated environment, such misinterpretations of the available data can trigger the execution of incorrect operations, which has the potential to cause great damage to the well being drilled and/or equipment associated with drilling the well.
Furthermore, accurate detection of a cementing stage allows events, categorized as “non-drilling” events (events that do not involve running a drillstring or casing down a borehole), to be detected. This, in turn, allows the time spent on those activities to be evaluated and so allows for optimization of the drilling process through comparison of performance between many jobs. Therefore, proper casing and/or cementing detection allows best practice management of “non-drilling” activities.